1. Field of the Invention
The present invention relates to roller lifter assemblies. More particularly, the present invention relates to the joining of a tie bar of between a first lifter body and a second lifter body of a roller lifter assembly. More particularly, the present invention relates to fastening techniques for preventing the rivet and the lifter bodies from rotating during the movement of the lifter bodies.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
An overhead valve engine is a type of piston engine that places the camshaft within the cylinder block and uses push rods to actuate rocker arms above the cylinder head to actuate the valves. The overhead valve engine is often referred to as a pushrod engine or an I-head engine. Lifters or tappets are located in the engine block between camshaft and the pushrods.
Typically, tappets or lifters are engineered to last a lifetime of the engine when the engine is properly maintained with proper oil and filter changes. On most overhead cam engines, the camshaft is directly over the valves. In some other overhead cam engines, a rocker arm pivots on a fixed shaft while one projection of the rocker arm rides on a cam of the rotating camshaft. In both cases, this creates an oscillating linear motion, opening the valve. The closing of the valve is typically accomplished by a compression spring placed between valve collet (or retainer) and the cylinder head above the combustion chamber. In overhead valve engines, the camshaft is located near the crankshaft and motion of the cam lobes is followed by cam followers (similar to lifters) and transferred up to the cylinder head and the rocker arm assembly by means of pushrods.
FIG. 1 shows a prior art roller lifter assembly. The roller lifter assembly in FIG. 1 includes a first lifter body 12 and a second lifter body 14. The first lifter body 12 has a roller 16 rotatably mounted at one end thereof. The second lifter body 14 has a roller 18 rotatably mounted at one end thereof. The rollers 16 and 18 are suitable for rolling along the lobes of the camshaft.
In FIG. 1, it can further be seen that there is a tie bar 20 that is longitudinal member that extends between the first lifter body 12 and the second lifter body 14. The tie bar 20 serves to connect the ends of the lifter bodies 12 and 14 opposite to that of the rollers 16 and 18. The buttons 22 and 24 are mounted over the tie bar 20 so as to secure the tie bar into a proper position. Typically, the tie bar will have a slightly slotted opening so as to receive the rivet shaft therein. The buttons 22 and 24 serve to secure the tie bar 20 into a proper position.
In FIG. 2, the opposite view of the roller lifter assembly 10 is shown. In FIG. 2, the first lifter body 12 and the second lifter body 14 are illustrated as connected to the tie bar 20. The ends of the roller lifter bodies 12 and 14 have a slightly concave surface. This concave end surface has an opening that receives rivets 26 and 28 therein. The rivets 26 and 28 will have a generally flat head with a flat undersurface that connects, by a shank, to the tie bar 20.
In the prior art illustrated in FIGS. 1 and 2, the tie bar 20 extends between the lifter bodies 12 and 14. Since the lifters will move upwardly and downwardly, a certain amount of twist will be associated with the lifters. The riveted connection of the tie bars to the lifter bodies attempts to prevent the lifters from rotating about a centerline. As such, there can be a certain amount of bending between the lifter bodies 12 and 14 and the tie bar. Eventually, a certain amount of rotation of the lifter bodies 12 and 14 will occur about the respective axes thereof. As such, a certain amount of binding will occur between the lifter bodies 12 and 14 and the tie bar 20. As such, a need has developed so as to establish a proper riveted connection between the tie bar and the lifter bodies which effectively prevents the lifter bodies from rotating, and eventually binding, with respect to the tie bar.
In the past, various patents have issued have issued relating to structures associated with rivets. U.S. Pat. No. 2,763,314, issued on Sep. 18, 1956 to R. H. Gill, shows an expansible hollow threaded rivet having a buttress portion to provide for increased resistance to shear. The rivet has a tubular body formed of a ductile material and uniform outside diameter. A generally flat head extends radially outwardly of the body at one end thereof.
U.S. Patent Publication No. 2007/0041783, published on Feb. 22, 2007 to M . Davis, describes a locking device for preventing rotation of one component relative to another component to which it is connected. The locking device comprises a locking plate having a component-engaging portion to engage one component. A surface of the locking plate is grooved to engage with the grooved surface carried by the other component. One or more fixing holes are provided for one or more fixing members to pass through in order to force the grooved surface of the locking plate into engagement with the grooved surface carried by the other component.
U.S. Pat. No. 4,741,298, issued on May 3, 1988 to G. E. Rhoads, describes a rollerized timing lifter for use in high performance engines. This lifter has a press-fit hydraulic mechanism utilizing an oil supply feed means from the roller body through and to the hydraulic mechanism. It has structure to maintain a self-adjusting lifter to zero valve lash due to engine wear and heat expansion. It further includes a method of altering valve timing automatically through an oil restricted oil bleed passage way leading to the pressure chamber so as to allow a leak down or delay of valve timing at low speeds.
U.S. Pat. No. 5,788,039, issued on Aug. 4, 1998 to Carpi et al., describes a clutch cover and clutch having such a cover. There are balancing holes for fixing a balancing device. At least one recess is formed in the cover adjacent to one of the balancing holes wherein the recess reduces the local thickness of the cover plate.
It is an object of the present invention to provide a roller lifter assembly that effectively avoids the rotation of the rivet during the movement of the lifter bodies.
It is another object of the present invention to provide a roller assembly that avoids the rotation of the rivet and maintains the centerline of the rivet in a generally fixed position.
It is another object of the present invention to provide a roller assembly that effectively prevents the binding of the roller lifter assembly.
It is still another object of the present invention to provide a roller assembly which is easy to manufacture, easy to install, and respectively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.